1.\" Copyright (c) 1988, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)strtok.3 8.2 (Berkeley) 2/3/94 33.\" $NetBSD: strtok.3,v 1.23 2008/08/29 05:48:40 dholland Exp $ 34.\" 35.Dd August 11, 2002 36.Dt STRTOK 3 37.Os 38.Sh NAME 39.Nm strtok, strtok_r 40.Nd string tokens 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In string.h 45.Ft char * 46.Fn strtok "char * restrict str" "const char * restrict sep" 47.Ft char * 48.Fn strtok_r "char *str" "const char *sep" "char **lasts" 49.Sh DESCRIPTION 50The 51.Fn strtok 52function 53is used to isolate sequential tokens in a nul-terminated string, 54.Fa str . 55These tokens are separated in the string by at least one of the 56characters in 57.Fa sep . 58The first time that 59.Fn strtok 60is called, 61.Fa str 62should be specified; subsequent calls, wishing to obtain further tokens 63from the same string, should pass a null pointer instead. 64The separator string, 65.Fa sep , 66must be supplied each time, and may change between calls. 67.Pp 68The 69.Fn strtok 70function 71returns a pointer to the beginning of each subsequent token in the string, 72after replacing the separator character itself with a 73.Dv NUL 74character. 75Separator characters at the beginning of the string or at the 76continuation point are skipped so that zero length tokens 77are not returned. 78When no more tokens remain, a null pointer is returned. 79.Pp 80The 81.Fn strtok_r 82function implements the functionality of 83.Fn strtok 84but is passed an additional argument, 85.Fa lasts , 86which points to a user-provided pointer which is used by 87.Fn strtok_r 88to store state which needs to be kept between calls to scan the same string; 89unlike 90.Fn strtok , 91it is not necessary to limit tokenizing to a single string at a time 92when using 93.Fn strtok_r . 94.Sh EXAMPLES 95The following will construct an array of pointers to each individual word in 96the string 97.Va s : 98.Bd -literal -offset indent 99#define MAXTOKENS 128 100 101char s[512], *p, *tokens[MAXTOKENS]; 102char *last; 103int i = 0; 104 105snprintf(s, sizeof(s), "cat dog horse cow"); 106 107for ((p = strtok_r(s, " ", &last)); p; 108 (p = strtok_r(NULL, " ", &last)), i++) { 109 if (i < MAXTOKENS - 1) 110 tokens[i] = p; 111} 112tokens[i] = NULL; 113.Ed 114.Pp 115That is, 116.Li tokens[0] 117will point to 118.Qq cat , 119.Li tokens[1] 120will point to 121.Qq dog , 122.Li tokens[2] 123will point to 124.Qq horse , 125and 126.Li tokens[3] 127will point to 128.Qq cow . 129.Sh SEE ALSO 130.Xr index 3 , 131.Xr memchr 3 , 132.Xr rindex 3 , 133.Xr strchr 3 , 134.Xr strcspn 3 , 135.Xr strpbrk 3 , 136.Xr strrchr 3 , 137.Xr strsep 3 , 138.Xr strspn 3 , 139.Xr strstr 3 140.Sh STANDARDS 141The 142.Fn strtok 143function 144conforms to 145.St -ansiC . 146The 147.Fn strtok_r 148function conforms to 149.St -p1003.1c-95 . 150.Sh BUGS 151The System V 152.Fn strtok , 153if handed a string containing only delimiter characters, 154will not alter the next starting point, so that a call to 155.Fn strtok 156with a different (or empty) delimiter string 157may return a 158.Pf non- Dv NULL 159value. 160Since this implementation always alters the next starting point, 161such a sequence of calls would always return 162.Dv NULL . 163